Seedling growth and survival of five tree species in secondary forests and adjacent pastures in the montane rain forests of southern Costa Rica

Ley-López, Juan Manuel; Ávalos, Gerardo; Chacón‐Madrigal, Eduardo

doi:10.15517/rbt.v64i4.22775

Cited by 5 publications

(6 citation statements)

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“…Higher recruitment rates observed during the 2015-2016 interval are likely to be directly associated with climatological changes, though they could potentially be an indirect result of previous disturbances that increase light. The importance of light availability to forest growth and dynamics is well known (Augspurger, 1984;Bentos, Nascimento, Vizcarra, & Williamson, 2017;Jakovac, Bentos, Mesquita, & Williamson, 2012), however responses still depend on specific requirements of each species (Ley-López, Avalos, & Chacón-Madrigal, 2016). Our study did not include direct metrics of light availability, however, we evaluated whether previous disturbances (i.e.…”

Section: Discussionmentioning

confidence: 99%

Palms and trees resist extreme drought in Amazon forests with shallow water tables

et al. 2020

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The intensity and frequency of severe droughts in the Amazon region have increased in the recent decades. These extreme events are associated with changes in forest dynamics, biomass and floristic composition. However, most studies of drought response have focused on upland forests with deep water tables, which may be especially sensitive to drought. Palms, which tend to dominate the less well‐drained soils, have also been neglected. The relative neglect of shallow water tables and palms is a significant concern for our understanding of tropical drought impacts, especially as one‐third of Amazon forests grow on shallow water tables (<5 m deep). We evaluated the drought response of palms and trees in forests distributed over a 600 km transect in central‐southern Amazonia, where the landscape is dominated by shallow water table forests (SWTF). We compared vegetation dynamics before and following the 2015–2016 El Nino drought, the hottest and driest on record for the region (−214 mm of cumulative water deficit). We observed no change in stand mortality rates and no biomass loss in response to drought in these forests. Instead, we observed an increase in recruitment rates, which doubled to 6.78% year‐1 ± 4.40 (M ± SD) during 2015–2016 for palms and increased by half for trees (to 2.92% year‐1 ± 1.21), compared to rates in the pre‐El‐Nino interval. Within these SWTF, mortality and recruitment rates varied as a function of climatic drought intensity and water table depth for both palms and trees, with mortality being greatest in climatically and hydrologically wetter environments and recruitment greatest in drier environments. Across our transect, there was a significant increase over time in tree biomass. Synthesis. Our results indicate that forests growing over shallow water tables—relatively under‐studied vegetation that nonetheless occupies one‐third of Amazon forests—are remarkably resistant to drought. These findings are consistent with the hypothesis that local hydrology and its interactions with climate strongly constrain forest drought effects, and has implications for climate change feedbacks. This work enhances our understanding of integrated drought effects on tropical forest dynamics and highlights the importance of incorporating neglected forest types into both the modelling of forest climate responses and into public decisions about priorities for conservation.

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Section: Discussionmentioning

confidence: 99%

Palms and trees resist extreme drought in Amazon forests with shallow water tables

et al. 2020

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“…Mart, con plantas de ocho meses de edad y 15 cm de altura en promedio, trasplantadas a macetas en condiciones de bosque y claros, después de haber sido desarrolladas en invernadero a media sombra, mostraron porcentajes de supervivencia superiores al 90 % en los primeros 180 días (Moretti et al, 2019), mientras que Sigala-Rodríguez et al (2015) en plantas de Pinus pseudostrobus, reportaron con plantas trasplantas de vivero con dos años de edad supervivencia inferior al 75 % en los primeros dos meses, inferior al 50 % a los tres meses e inferior al 25 % en los cuatro meses, con un promedio del 4,2 % al final de catorce meses. Estudios realizados en cinco especies sembradas en invernadero y trasplantadas bosque secundario por Ley-López et al (2016), indicaron porcentajes de supervivencia entre el 30 al 90 %, después de un año de crecimiento.…”

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Germination and growth of Sterculia colombiana in Arosemena Tola, Napo, Ecuador

et al. 2023

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Introduction. The Amazon region has a great plant diversity, but studies on their propagation and growth have been carried out in few species. Objective. To evaluate the in situ and ex situ germination of Sterculia colombiana and its growth characteristics after planting in ground covers of primary forest and intervened areas. Materials and methods. The study was carried out in Napo, Ecuador, in the period 2019-2020. The germination of S. colombiana was characterized in the variables: days and percentage to emergence, plant height, stem diameter and number of leaves, under greenhouse conditions and planted at the collection site. The plants obtained in the germination test were transplanted to a ground cover of primary forest (in situ) and an intervened area with replacement vegetation (ex situ). Linear, quadratic, cubic, exponential, and logarithmic growth models for stem height and diameter were evaluated. The air and soil temperature and the physical-chemical characteristics of the soil were recorded. An analysis of variance was performed to determine differences in growth and survival between the plantation sites and between the plants obtained in the in situ and ex situ tests. Results. The seedlings obtained from greenhouses reported fewer days to emergence and higher values in the rest of the variables evaluated than those grown in situ. The plants developed in the different evaluated covers, without significant differences in growth at the end of the study, only a significant correlation at 5 % between stem diameter and air temperature was reported. Conclusions. Sterculia colombiana germinated in a greenhouse and developed in the transplant sites, without this influencing its growth. Temperature was the only factor that reported significant correlations with growth at the end of the evaluation period.

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“…Large-seeded species were less likely to establish with increasing surface temperatures in contrast to small-seeded species indicating that large-seeded species are more vulnerable to extreme temperatures. Surface temperatures and soil moisture have been identified as the most influential environmental factors for seedlings, showing that abiotic conditions drive differences in seedling recruitment between habitats (Chacón et al, 2016;Peña-Domene et al, 2017). Previous studies have pointed out that abiotic conditions in pastures drive higher mortality of seedlings (Chacón et al, 2016;Eriksson & Eriksson, 1997).…”

Section: Resultsmentioning

confidence: 99%

“…Second, I expected that there will be generally more seedlings recruiting in the forest compared to pastures and that large-seeded species would more successfully recruit in the forest due to harsh abiotic conditions in the pastures (Chacón et al, 2016;Eriksson & Eriksson, 1997). Third, I expected that high temperatures and biotic pressures would reduce recruitment success of both groups of seedlings with more pronounced response in small-seeded species Engelbrecht et al, 2005).…”

Section: How Does Seedling Recruitment Of Small-and Large-seeded Spec...mentioning

confidence: 99%

Trait-dependent effects of biotic and abiotic filters on plant regeneration in Southern Ecuador

Barczyk

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Tropical forests have always fascinated scientists due to their unique biodiversity. However, our understanding of ecological processes shaping the complexity of tropical rainforests is still relatively poor. Plant regeneration is one of the processes that remain understudied in the tropics although this is a key process defining the structure, diversity and assembly of tropical plant communities. In my dissertation, I combine experimental, observational and trait-based approaches to identify processes shaping the assembly of seedling communities and compare associations between environmental conditions and plant traits across plant life stages. By working along a steep environmental gradient in the tropical mountains of Southern Ecuador, I was able to investigate how processes of plant regeneration vary in response to biotic and abiotic factors in tropical montane forests. My dissertation comprises three complementary chapters, each addressing an individual research question. First, I studied how trait composition in plant communities varies in relation to the broad- and local-scale environmental conditions and across the plant life cycle. I measured key traits reflecting different ecological strategies of plants that correspond to three stages of the plant life cycle (i.e., adult trees, seed rain and recruiting seedlings). I worked on 81 subplots along an elevational gradient covering a large climatic gradient at three different elevations (1000, 2000 and 3000 m a.s.l.). In addition, I measured soil and light conditions at the local spatial scale within each subplot. My findings show that the trait composition of leaves, seeds and seedlings changed similarly across the elevational gradient, but that the different life stages responded differently to the local gradients in soil nutrients and light availability. Consequently, my findings highlight that trait-environment associations in plant communities differ between large and small spatial scales and across plant life stages. Second, I investigated how seed size affects seedling recruitment in natural forests and in pastures in relation to abiotic and biotic factors. I set up a seed sowing experiment in both habitat types and sowed over 8,000 seeds belonging to seven tree species differing in seed size. I found that large-seeded species had higher proportions of recruitment in the forests compared to small-seeded species. However, small-seeded species tended to recruit better in pastures compared to large-seeded species. I showed that high surface temperature was the main driver of differences in seedling recruitment between habitats, because it limited seedling recruitment of large-seeded species. The results from this experiment show that pasture restoration requires seed addition of large-seeded species and active protection of recruiting seedlings in order to mitigate harmful conditions associated with high temperatures in deforested areas. Third, I examined the associations between seedling beta-diversity and different abiotic and biotic factors between and within elevations. I applied beta-diversity partitioning to obtain two components of beta-diversity: species turnover and species richness differences. I associated these components of beta-diversity with biotic pressures by herbivores and fungal pathogens and environmental heterogeneity in light and soil conditions. I found that species turnover in seedling communities was positively associated with the dissimilarity in biotic pressures within elevations and with environmental heterogeneity between elevations. Further, I found that species richness differences increased primarily with increasing environmental heterogeneity within elevations. My findings show that the associations between beta-diversity of seedling communities and abiotic and biotic factors are scale-dependent, most likely due to differences in species sorting in response to biotic pressures and species coexistence in response to environmental heterogeneity. My dissertation reveals that studying processes of community assembly at different plant life stages and spatial scales can yield new insights into patterns and processes of plant regeneration in tropical forests. I investigated how community assembly processes are governed by abiotic and biotic filtering across and within elevations. I also experimentally explored how the process of seedling recruitment depends on seed size-dependent interactions, and verified how these effects are associated with abiotic and biotic filtering. Identifying such processes is crucial to inform predictive models of environmental change on plant regeneration and successful forest restoration. Further exploration of plant functional traits and their associations with local-scale environmental conditions could effectively support local conservation efforts needed to enhance forest cover in the future and halt the accelerating loss of biodiversity.

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Seedling growth and survival of five tree species in secondary forests and adjacent pastures in the montane rain forests of southern Costa Rica

Cited by 5 publications

References 72 publications

Palms and trees resist extreme drought in Amazon forests with shallow water tables

Palms and trees resist extreme drought in Amazon forests with shallow water tables

Germination and growth of Sterculia colombiana in Arosemena Tola, Napo, Ecuador

Trait-dependent effects of biotic and abiotic filters on plant regeneration in Southern Ecuador

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